CAMS2021 Seminar Series
26 October 2021 | 10am AEDT
'Accounting for the effect of dislocation climb-mediated flow on the anisotropy and texture evolution of Mg alloys'
Speaker: Sean Agnew, Professor of Materials Science & Engineering, University of Virginia
CAMS2021 is part of an ongoing series of meetings that are the product of the cooperation between two eminent materials professional societies in Australia – Materials Australia (MA) and the Australian Ceramic Society (ACS).
This year the 7th conference of the Combined Australian Materials Societies (CAMS2021) was to be hosted in Melbourne, Australia in December. However, the present situation in Australia has forced the organising committee to postpone this event to 02-04 February 2022.
In place, the organising committee offers members of these two societies and those already registered for CAMS2021 the opportunity to attend a seminar series where prominent international researchers will present their latest research results to the Australian material research communities.
This seminar series will take place over several weeks between October and December and will be a live, online-only (zoom) event for members of the two societies, featuring invited lectures from international researchers, and it will not be recorded.
You must be a member of Materials Australia or the Australian Ceramic Society, have registered for CAMS2021 (or submitted an abstract) to attend these seminars.
CAMS2021 Registration (02-04 February 2022): www.cams2021.com.au
Join as an Individual Member here ($240)
Join as a Student Member here ($30)
Speaker Details
Sean R. Agnew earned a B.S. in Mechanical Eng. and Materials Science and Eng. (MSE) from Cornell University (1993) and Ph.D. in MSE from Northwestern University (1998). He received a Eugene P. Wigner Postdoctoral Fellowship at the Oak Ridge National Laboratory in 1999, was the first Helmholtz Zentrum Geesthacht Magnesium Research Award winner in 2008, was named the Heinz & Doris Wilsdorf Chaired Associate Professor of MSE in 2010, became a Fellow of ASM international in 2015, has served as Associate Editor of the International Journal of Plasticity since 2018, and was recently named the William G. Reynolds Chaired Professor of MSE at the University of Virginia, where he has served on the faculty since 2001. He specializes in electron, X-ray, and neutron scattering-based characterization of materials structure, mechanical property characterization, and computational modeling of the mechanical behaviors of a diverse range of materials: from lightweight metals and alloys (Al, Be, Mg and Ti), to TiC-based cermets, all the way to heavier metals and alloys which are important for particle accelerators, biomedical, aerospace, energy applications, and defense (Cu, high purity Nb, Nb alloys, Mo-Re, Re, U, U-Mo, U-Nb). He is presently exploring GP-zone strengthened Mg alloys, the interactions between phonons and crystal defects, non-destructive testing, additive manufacturing, compositionally complex alloys, materials development for extreme environments, high energy synchrotron x-ray diffraction-based in-situ measurements within individual grains, and neutron diffraction contrast tomography.
Abstract
There has recently been active research into nearly every aspect of Mg metallurgy: extraction, alloy development, casting, thixomoulding, deformation processing, forming, corrosion resistance and coating. While much of the research has focused on lightweighting of transportation technologies to improve efficiency, some focuses on consumer goods, biomedical applications, and batteries. Many have sought to improve the castability, corrosion and creep resistance, and formability. The present research seeks to better understand the fundamental mechanisms which control creep and forming performance. We specifically investigate the role that dislocation climb has in mediating plasticity at moderate temperatures, where the ductility of Mg alloys can be excellent. Mechanical tests were performed on Mg alloy samples over a range of strain rates and temperatures. Experimental measurements of the resulting anisotropy (r-value) and texture evolution were used as constraints for a genetic algorithm-based parametric study employing a new crystal plasticity model, which explicitly accounts for the kinematics of dislocation climb. The results reveal that the climb of basal < a > dislocations is not only important for recovery, but also accommodates a significant fraction of the strain under power-law creep conditions. This work does not discredit the notion that non-basal slip of is important. However, it demonstrates that the major mechanistic change that occurs upon power law breakdown, the activation of dislocation climb, provides an explanation for an even wider range of observations. It is hypothesized that these conclusions may even apply to cases in which grain boundary sliding and/or dynamic recrystallization are observed.
CAMS2021 Registration (02-04 February 2022): www.cams2021.com.au